I went with camo for all first and that was a good move. Second one was repair, and IMHO it is a waste of a skill slot even when they all reached 100%. On this tank view is key. So I dropped the repairs and radioman got Sit Awareness, Commander: Eagle Eye, Driver: off-road driving, Loader: Safe Stowage. Gunner: Designated Target. Then I dropped the camo from commander and replaced it with Sixth Sense. Commander is now working back the camo @ 45%

To me Camo is the key skill to reach because PzIV (according to WoTdb) has a quite high camo rating to begin with. I've often stayed hidden - things do seem to have changed a bit since 7.4, I get detected rather often whereas I would think I'd have been safe.

Eagle Eye: That is a very good perk. Helps you identify crippled tanks and sometimes allows you to make decisions based on that. Damaged gun? You stand a good chance in open fight, Radio? you could maybe relocate w/o rest of their team knowing, etc. I love this perk.

Sixth Sense. This is a goddamned live saver, especially for a sniper. You know exactly when to move away or stay hidden or whether or not you can safaly advance to the next spot.

Off Road driving: This is a good skill, really maikes noticeable difference in driving on all but city maps with paved roads (IOW majority of maps).

Designated target: That's pretty good too. For a hidden sniper those 2 seconds often mean you can get a shot off into a target as opposed to blind shot into last known position.

To me, it depends entirely on whether you plan to keep this crew in the Pz IV or move them on to subsequent tanks. I have my Pz IV crew trained in camo, but that would be dumb for a VK36 or VK3002, or any of the heavy tanks.